Preview system for an electrophotographic printing machine

ABSTRACT

An electrophotographic printing machine in which an edited copy of an original document is formed. A video image of the original document is displayed and the machine operator adjusts the image as desired. After being adjusted, an edited copy of the video image is reproduced by the printing machine.

This invention relates generally to an electrophotographic printingmachine, and more particularly concerns a system for previewing the copyof the original document being reproduced by the printing machine.

In general, the process of electrophotographic printing includescharging a photoconductive member to a substantially uniform potentialto sensitize the surface thereof. The charged portion of thephotoconductive surface is exposed to a light image of an originaldocument being reproduced. In this way, an electrostatic latent image isrecorded on the photoconductive surface which corresponds to theinformation desired to be reproduced. After recording the electrostaticlatent image on the photoconductive member, the latent image isdeveloped by bringing developer material into contact therewith.Generally, the developer material comprises toner particles adheringtriboelectrically to carrier granules. The toner particles are attractedfrom the carrier granules to form a toner powder image on thephotoconductive member which is subsequently transferred to a copysheet. Finally, the copy sheet is heated to permanently affix the powderimage thereto in image configuration.

Recently, it has become desirable to edit the original document beingreproduced in the copying machine. This may be greatly facilitated bypreviewing the resultant copy. Thus, it would be highly desirable to becapable of displaying the copy electronically prior to the actualformation of the hard copy so that the machine operator can perform anydesired editing on the electronic copy being displayed. For example, ifthe copy of the original document is enlarged or reduced, thecorresponding electronic image being displayed would also be enlarged orreduced according to the optics enlargement/reduction ratio selected andthe size of the copy sheet. Thus, the electronic display of the copyseen by the operator corresponds exactly to the resultant hard copyproduced by the printing machine. Similarly, other features may also bedisplayed electronically. For example, the displayed image could showoperator selected image shift. In addition, the result of deleting oradding information could also be shown. Furthermore, the effect ofmaking the copy darker or light may also be displayed. Thus, it is clearthat previewing the copy of the original document allows the measurementand adjustment of a number of operating parameters, e.g. contrast, tonerconsumption, document size and position. Moreover, the ability topreview the copy of the original document permits the effect of thevarious editing commands, e.g. reduction/enlargement, margin settings,and text deletion/addition to be seen by the machine operator.

Various techniques have been devised to achieve the foregoing. Thefollowing disclosures appear to be relevant:

    ______________________________________                                        U.S. Pat. No. 4,153,364                                                       Patentee: Suzuki et al.                                                       Issued: May 8, 1979                                                           U.S. Pat. No. 4,239,374                                                       Patentee: Tatsumi et al.                                                      Issued: December 16,1980                                                      U.S. Pat. No. 4,375,916                                                       Patentee: Levine                                                              Issued: March 8, 1983                                                         U.S. Pat. No. 4,616,269                                                       Patentee: Mori                                                                Issued: October 7, 1986                                                       German OLS DE 3,429,549 A1                                                    Applicant: Yatanade                                                           Published: February 28, 1985                                                  Japanese Patent Appln. No. 60.85676                                           Applicant: Nishiguchi                                                         Published: May 15, 1985                                                       ______________________________________                                    

The pertinent portions of the foregoing disclosures may be brieflysummarized as follows:

Susuki et al. and Tatsumi et al. teach the use of photosensors to detectprint density and the format on a page. This, in turn, is used tomeasure various operating parameters within the printing machine, forexample, exposure illumination and density, developer bias voltage, etc.

Levine discloses a portable image reader/recorder with a displayallowing adjustment of the various parameters. The reader is connectedto a compatible electrophotographic printing machine to produce aprintout of the recorded image.

Mori describes a technique for optically displaying an original documenton a screen to allow the operator to set the margins and various otherfunctions of the copy.

Yatanade discloses a charge coupled device (CCD) array in the opticalpath of an electrophotographic printing machine to drive a liquidcrystal display (LCD display) indicating the size and position of theoriginal document.

Nishiguchi teaches a facsimile device which will display a receivedimage on a screen prior to the printing thereof.

In accordance with one aspect of the features of the present invention,there is provided an electrophotographic printing machine for forming acopy of an original document. The printing machine includes aphotoconductive member. Means are provided for charging at least aportion of the photoconductive member. Means sense an optical image andgenerate an electrical video image in response thereto. Means form alight image of the original document. The forming means projects thelight image of the original document onto the sensing means to producean electrical image thereof and projects the light image of the originaldocument onto the charged portion of the photoconductive member torecord an electrostatic latent image of the original document thereon.

Other aspects of the present invention will become apparent as thefollowing description proceeds and upon reference to the drawings inwhich:

FIG. 1 is a schematic elevational view showing an electrophotographicprinting machine incorporating the features of the present inventiontherein; and

FIG. 2 is a schematic elevational view showing a block diagram of thesystem for controlling the various parameters of the processing stationsin the FIG. 1 electrophotographic printing machine.

While the present invention will hereinafter be described in conjunctionwith a preferred embodiment thereof, it will be understood that it isnot intended to limit the invention to that embodiment. On the contrary,it is is intended to cover all alternatives, modifications andequivalents as may be included within the spirit and scope of theinvention as defined by the appended claims.

For a general understanding of the features of the present invention,reference is made to the drawings. In the drawings, like referencenumerals have been used throughout to designate identical elements. FIG.1 schematically depicts the various components of an electrophotographicprinting machine incorporating the features of the present inventiontherein. It will become evident from the following discussion that thepresent invention is not limited in its application to the particularembodiment depicted herein.

Inasmuch as the art of electrophotographic printing is well known, thevarious processing stations employed in the FIG. 1 printing machine willbe shown hereinafter schematically and their operation described brieflywith reference thereto.

As shown in FIG. 1, the electrophotographic printing machine employs adrum 10 having a photoconductive surface 12. Preferably, photoconductivesurface 12 is made from a selenium alloy deposited on a conductivesubstrate, such as an aluminum alloy. Drum 10 moves in the direction ofarrow 14 to advance successive portions of photoconductive surface 12sequentially through the various processing stations disposed about thepath of movement thereof.

In operation, the operator may select the number of copies beingreproduced as well as being capable of adjusting any of the parameterswithin the various processing stations. This is achieved by keying inthe required adjustment and number of copies at the control panel,indicated generally by the reference numeral 16. Control panel 16 iselectrically coupled to a centralized processing unit, indicatedgenerally by the reference numeral 18. Preferably, centralizedprocessing unit (CPU) 18 is a microprocessor made by Intel Corporationunder the Model No. 8086. CPU 18 is electrically connected to thevarious processing stations within the electrophotographic printingmachine so as to control their operation. In addition, CPU 18 iselectrically coupled to a video display, indicated generally by thereference numeral 20. Display 20 is adapted to display the resultantcopy electronically. Thus, Display 20 displays an electrical video imageof the resultant copy of the original document. The electrical videoimage displayed shows the effects of the various manipulations performedthereon by the operator through the utilization of control panel 16. Forexample, if the operator elects to have an enlarged or reduced copy, thedisplayed copy will correspond to the desired enlargement or reductionof the original document. Alternatively, if the operator elects todelete selected portions from the original document in the copy, thedisplayed video image will show the copy with the portions of theoriginal document delected therefrom. Thus, display 20 provides apreview of the resultant copy to the operator prior to the formation ofthe hard copy thereof.

With continued reference to FIG. 1, initially, a portion ofphotoconductive surface 12 passes through a charging station. At thecharging station, a corona generating device, indicated generally by thereference numeral 22, charges photoconductive surface 12 to a relativelyhigh substantially uniform potential.

Next, the charged portion of photoconductive surface 12 is advancedthrough an imaging station. The imaging station includes an exposuresystem, indicated generally by the reference numeral 24. In exposuresystem 24, an original document 26 is positioned face down on atransparent platen 28. Lamp 30 move across platen 28 to illuminatesuccessive incremental areas of original document 26. The light raysreflected from original document 26 are reflected from mirror 32 throughlens 34 and lens 35 to form a light images thereof. The light imagetransmitted through lens 35 is transmitted to a solid stateoptical-electrical panel, such as a charged couple device matrix orarray (CCD array), indicated generally by the reference numeral 38, orthe like. Mirror 32, lens 35, CCD array 38, and lens 34 move in a timedrelationship with lamps 34 so as to be in the proper relationship withrespect thereto for forming the light image. Mirror 36 is positioned inthe light path of the light image transmitted through lens 36. The lightimage transmitted through lens 34 is reflected by mirror 36 onto thecharged portion of photoconductive surface 12 to record an electrostaticlatent image thereon corresponding to the original document. In order topreview the copy, CCD array 38, in response to the light imagetransmitted thereto through lens 35 generates an electrical video imagecorresponding to the original document. CCD array 38 is electricallycoupled to CPU 18. CPU 18, in turn, is connected electrically to controlpanel 16. The operator selects the variations desired in the copythrough the use of control panel 16 which, in turn, transmits electricalsignals indicative thereof to CPU 18. CPU 18 adjusts the electricalvideo image transmitted from CCD array 38 to correspond with the changestransmitted thereto from control panel 16. The adjusted electrical videoimage is then transmitted from CPU 18 to display 20, which may be acathode ray tube (CRT) or a liquid crystal display. CRT 20 displays thedesired copy. Prior to the operator performing any control functionthrough the utilization of control panel 16, CRT 20 displays theun-adjusted copy which corresponds to the original document as it willbe reproduced After the operator introduces the desired adjustments tothe original document, CRT 20 displays the adjusted copy thereon. CPU 18is also electrically connected to the various processing stations in theprinting machine. In this way, CPU 18 controls these processing stationsto produce the operator selected adjustments to the copy of the originaldocument.

In the copying mode, the electrostatic latent image is recorded on thephotoconductive surface. This is achieved by mirror 36 positioned in thepath of the light image transmitted from lens 34 so as to reflect thelight image of the original document onto the charged portion ofphotoconductive surface 12. The region between successive electrostaticlatent images and the lateral marginal regions of the electrostaticlatent image are discharged by erase lamp 40. Erase lamp 40 also acts todelete selected portions of the electrostatic latent image in responseto the appropriate command from the CPU 18. Erase lamp 40 comprises aplurality small lamps which may be independently energized to eliminateselected portions of the electrostatic latent image recorded onphotoconductive surface or any charged portion of photoconductivesurface 12. Alternatively, erase lamp 40 may be made from a plurality oflight emitting diodes (LEDs). The lamps of erase lamp 40 extend acrossthe width of drum 10 in a direction substantially parallel to thelongitudinal axis thereof. Erase lamp 40 is electrically connected toCPU 18. In order to delete selected portions of the original document inthe copy, the operator, through the use of control panel 16, defines thecoordinates or portions of the original document to be deleted from thecopy. As previously indicated, in the preview mode of operation, theoriginal document is displayed on CRT 20. CRT 20 has X and Y axes orscales thereon. Thus, the operator can readily determine the coordinatesof the portion of the original document to be deleted. On control panel16, the operator presses edit key 42 to place control panel 16 in theedit mode of operation. Thereafter, the operator depresses numeral keys44 to define the X and Y coordinates of the portion of the originaldocument to be delected from the copy. Electrical signals from numeralkeys 44 corresponding to the coordinates of the original document to bedeleted from the copy are transmitted to CPU 18. This information isused to control the selective, independent energization of the lampswhich make up erase lamp 40. This defines the duration of time that eachof the erase lamps 40 are energized. Thus, the selected lamps are turnedon at the appropriate time to delete the desired portion of theelectrostatic latent image so that the resultant copy has the selectedportion of the original document deleted therefrom. Furthermore, theindividual lamps of erase lamp 40 are energized to discharge the regionbetween electrostatic latent images, i.e. the inter-image region. Inaddition, side lamps are continuously energized to discharge the lateralmarginal region of the drum outside the area of the electrostatic latentimage on the side portions thereof. One skilled in the art willappreciate that the input of the coordinates to be deleted is notlimited to keys. Cursor and other position appointing members may beused for the same purpose. If it is desired to form a color highlightedcopy, the portion to be reproduced in the highlight color is deleted inaccordance with the preceeding procedure to form a first editedelectrostatic latent image. A second electrostatic latent image of theoriginal document has the other portion, i.e. the area to be reproducedin black, deleted therefrom to form a second electrostatic latent image.The edited electrostatic latent image is advanced on drum 10 todevelopment station C.

At the development station C, a magnetic brush development system,indicated generally by the reference numeral 46, includes a firstdeveloper unit, indicated generally by the reference numeral 47, and asecond developer unit, indicated generally by the reference numeral 49.Developer unit 47 is adapted to develop the electrostatic latent imagewith black toner particles while developer unit 49 is adapted to developthe electrostatic latent image with toner particles of a color otherthan black, e.g. red. Developer unit 47 includes at least one developerroller, indicated generally by reference numeral 48, for transporting adeveloper material of carrier granules having toner particles adheringtriboelectrically thereto into contact with the electrostatic latentimage. Developer roller 48 is made from a non-magnetic sleeve having astationary magnetic disposed interiorly thereof. The non-magnetic sleeveis electrically biased. As the non-magnetic sleeve rotates, thedeveloper material is attracted thereto and transported into contactwith the electrostatic latent image recorded on photoconductive surface12. The exterior circumferential surface of the non-magnetic sleeve isroughened. By way of example, the non-magnetic sleeve is made preferablyfrom aluminum with the magnet being made from barium ferrite. A voltagesource is coupled to the non-magnetic sleeve. The output from thevoltage source is controlled by the CPU 18. Thus, CPU 18 is electricallycoupled to the voltage source which regulates the electrical bias on thenon-magnetic sleeve of developer roller 48. Developer unit 49 includesat least one developer roller, indicated generally by reference numeral51, for transporting a developer material of carrier granules havingtoner particles adhering triboelectrically thereto into contact with theelectrostatic latent image. Developer roller 51 is made from anon-magnetic sleeve having a stationary magnetic disposed interiorlythereof. The non-magnetic sleeve is electrically biased. As thenon-magnetic sleeve rotates, the developer material is attracted theretoand transported into contact with the electrostatic latent imagerecorded on photoconductive surface 12. The exterior circumferentialsurface of the non-magnetic sleeve is roughened. By way of example, thenon-magnetic sleeve is made preferably from aluminum with the magnetbeing made from barium ferrite. A voltage source is coupled to thenon-magnetic sleeve. The output from the voltage source is controlled bythe CPU 18. Thus, CPU 18 is electrically coupled to the voltage sourcewhich regulates the electrical bias on the non-magnetic sleeve ofdeveloper roller 51. CPU 18 controls the energization of eitherdeveloper unit 47 or developer unit 49 to develop the electrostaticlatent image. The developer units are move from a position remote fromthe photoconductive surface to an operative position adjacent thereto.In the preview mode of operation, the operator may actuate theappropriate key on control panel 16 to adjust the contrast of the copy.Thus, the copy may be made darker or lighter. This is achieved byadjusting the electrical bias on developer roller 48. Hence, theoperator selects the appropriate key, i.e. the darker or lighter key,and the voltage source coupled to developer roller 48 is adjusted so asto set the electrical bias on the developer roller at the desired level.Alternatively, copy contrast may be adjusted by regulating the intensityof the exposure lamps 30 or the charge level produced by coronagenerating device 22.

After development, drum 10 advances the toner powder image to thetransfer station. At the transfer station, a sheet of support materialis moved into contact with the powder image. The sheet of supportmaterial is advanced to transfer station D by a sheet feeding apparatus,indicated generally by the reference numeral 50. Preferably, sheetfeeding apparatus 50 includes a feed roll 52 contacting the uppermostsheet of a stack of sheets 54. Feed roll 52 rotates in the direction ofarrow 56 so as to advance the uppermost sheet into the nip defined byforwarding rollers 58. Forwarding rollers 58 rotate in the direction ofarrow 60 to transport the sheet into chute 62. Chute 62 directs theadvancing sheet of support material into contact with photoconductivesurface 12 of drum 10 so that the toner powder image developed thereoncontacts the advancing sheet at the transfer station.

Preferably, the transfer station includes a corona generating device 64which sprays ions onto the backside of the sheet. This attracts thetoner powder image from photoconductive surface 12 to the sheet. Aftertransfer, the sheet continues to move on conveyor 66, in the directionof arrow 68, to fusing station E.

Fusing station E includes a fuser assembly, indicated generally by thereference numeral 70 which permanently affixes the transferred tonerpowder image to the sheet. Preferably, fuser assembly 70 includes aheated fuser roller 72 and a back-up roller 74. The sheet passes betweenfuser roller 72 and back-up roller 74 with the powder image contactingfuser roller 72. In this manner, the powder image is permanently affixedto the sheet. After fusing, forwarding rollers 76 advance the sheet tocatch tray 78 for subsequent removal from the printing machine by theoperator. If a color highlight copy is being produced, the sheet isrecirculated to the transfer station so that the next toner powder imagemay be transferred thereto. Thereafter, the sheet passes through thefusing station to permanently affix this powder image thereto and theresultant highlight color copy advances to catch tray 78.

After the powder image is transferred from photoconductive surface 12 tothe copy sheet, drum 10 rotates the photoconductive surface to cleaningstation F. At cleaning station F, a magnetic brush cleaning systemremoves the residual particles adhering to photoconductive surface 12.The magnetic rush cleaning system transports carrier granules closelyadjacent to the photoconductive surface to attract residual tonerparticles thereto. In this way, the residual particles are removed fromphotoconductive surface 12 prior to initiation of the next successiveimaging cycle.

It is believed that the foregoing description is sufficient for purposesof the present invention to illustrate the operation of anelectrophotographic printing machine incorporating the features of thepresent invention therein. Referring now to FIG. 2, the details of thecontrol scheme associated with the capability to preview the resultantcopy will be discussed.

As shown in FIG. 2, if the operator desires to edit the copy of theoriginal document, edit key 42 of control panel 16 is depressed.Thereafter, the operator selects the appropriate keys 44 which arenumeral keys for inputting the coordinates of the portion of theoriginal document to be deleted from the copy. As previously indicated,the unedited original document is displayed on CRT 20. Scales on CRT 20enable the operator to readily select the coordinates of the portion ofthe copy to be deleted. The operator now depresses the appropriatenumeral keys 44 to define these coordinates. This information is thentransmitted electrically from control panel 16 to CPU 18. CPU 18, inturn, now energizes the appropriate lamps of erase lamp 40 so as toeffect the desired deletion from the electrostatic latent image recordedon photoconductive surface 12 of drum 10. The electrostatic latent imageis recorded on photoconductive surface 12 of drum 10 by the operator bydepressing key 80 which switches the copying machine from the previewingor editing mode to the copying mode. As previously noted, CCD array 38transmits an electrical video signal to CPU 18 which, in turn, energizesCRT 20 to display the original document thereon. As the operator affectsadjustments, these adjustments are displayed on CRT 20 so that theresultant video image corresponds substantially to the resultant copythat will be reproduced by the electrophotographic printing machine. Asshown in FIG. 2, CCD array 38 transmits the electrical video signal toCPU 18 which, in turn, generates an adjusted electrical video signal toCRT 16 for display. If the copy contrast is desired to be changed, theoperator will selected the appropriate key to either increase ordecrease the copy contrast. A signal is transmitted from control panel16 to CPU 18. CPU 18, in turn, adjusts the voltage source of the biascontrol system, indicated generally by the reference numeral 82. Thisincreases or decreases the electrical bias of either developer roller48, lamps 30, or corona generator 22. In addition to controlling thecontrast of the copy, CPU 18 also regulates toner dispensing as afunction of the percentage of area requiring writing thereon. Thus, theCCD array 38 transmits an electrical video image of the originaldocument to CPU 18. Control panel 16 transmits the operator selectedadjustments to CPU 18. CPU 18 generates an electrical signalcorresponding to the adjusted copy. CPU 18 determines the percentage ofthe adjusted copy that will require toner particles. In this way, thecentralized processing unit regulates dispensing of toner particles froma toner hopper into the sump of developer units 47 and 49. Thecentralized processing unit will control the electrical circuit andmotor associated with rotating a foam roller in the opening of the tonerhopper of each of the developer units to discharge toner particlestherefrom into the sump of developer unit. Thus, CPU 18 controls tonerdispensing control circuit 84 to regulate the concentration of tonerparticles within the developer units. This maintains the concentrationof toner particles within the developer mixture, i.e. the ratio of tonerparticles to carrier granules substantially constant. The details ofthis type of toner dispensing system are described in co-pending U.S.patent application Ser. No. 925,578 filed on Oct. 31, 1986, the relevantportions thereof being hereby incorporated into the present application.One skilled in the art will appreciate that many other types of controlschemes may be employed to regulate the discharge of toner particlesunder the control of CPU 18.

If it is desired to adjust the magnification of the copy, the operatordepresses key 86 or 88 to either enlarge or reduce the resultant copy.This results in an electrical signal being transmitted from controlpanel 16 to CPU 18 indicating the required enlargement/reduction. CPU18, in turn, controls reduction/enlargement control circuit 90 toregulate exposure system 24 to effect the desired enlargement orreduction of the original document on the copy. In the preview mode ofoperation, CRT 20 displays the resultant adjusted copy having theselected enlargement or reduction.

Still another adjustment may be to shift the image on the copy sheetsideways, i.e. so as to produce a desired side margin, for example, topunch holes in the copy sheet or to facilitate binding or stapling astack of sheets to one another. The image shift control circuit 92 isalso controlled by CPU 18. The operator selects the appropriate key oncontrol panel 16 and transmits and electrical signal to CPU 18indicating that an image shift should be affected. Centralizedprocessing unit 18, in turn, regulates image shift control circuit 92which, in turn, controls exposure system 24 to effect the desired shiftof the image. Once again, in the previewing mode, the shift of the imageon the copy sheet is displayed on the cathode ray tube.

A further application of the present invention includes the addition oftext to the copy. This may be achieved by a printing machine including alaser system for writing on the charged photoconductive surface. Akeyboard coupled to CPU 18k generates the desired text. CPU 18, in turn,transmits electrical signals to CRT 20 to display the text on the videoimage of the copy. Thus, the operator may now view the final copy withthe text added thereto. CPU 18 also modulates the laser system to writethe text on the charged photoconductive surface forming an electrostaticlatent image thereof. The latent image is developed and the added testtransferred to the copy sheet having the desired information from theoriginal document thereon. In this way, editing includes addinginformation e.g. text, as well as adjusting the parameters of the copy,and producing highlight color copies, or any other variations or changesto the copy of the original document.

It is clear that the centralized processing unit may be utilized tocontrol any of the various processing stations within theelectrophotographic printing machine. Thus, in the adjustment stage, theoperator selects the desired adjustment on control panel 16. Controlpanel 16 transmits an electrical signal corresponding to the requiredchange to CPU 18. CPU 18, in turn, regulates the appropriate processingstation to effect the desired adjustment to the copy. The adjustment tothe copy is displayed to the operator on the cathode ray tube.

After the operator has affected the desired changes, copying key 80 isdepressed. Thereafter, the operator selects numeral keys 42 to specifythe number of edited copies to be reproduced. Thus, theelectrophotographic printing machine will reproduce the requisite numberof edited copies. For example, if the operator desires five copieshaving a portion of the original document deleted therefrom, afterselecting editing button 42 and defining the coordinates of the portionof the original document to be deleted, the operator selects copying key80 and, thereafter, the numeral key 44 corresponding to the desirednumber of copies. This actuates the electrophotographic printing machineto produce the desired number of copies which have the selected portionof the original document deleted therefrom.

In recapitulation, it is evident that an electrophotographic printingmachine having the features of the present invention incorporatedtherein is capable of operating in both a preview mode and a copyingmode. In the previewing mode of operation, the operator is initiallyshown a display of the unadjusted copy of the original document. Theoperator then actuates the appropriate keys on the control panel to editthe copy. The edited copy is now displayed to the operator. When theoperator is satisfied with the edited copy, the appropriate copying keyis energized on the control panel so that the printing machine isswitched to the copying mode of operation. The operator now selects thenumber of copies to be reproduced and the machine is actuated toreproduce the desired number of edited copies.

It is evident, that there has been provided in accordance with thepresent invention an electrophotographic printing machine that fullysatisfies the aims and advantages hereinbefore set forth. While thisinvention has been described in conjunction with a preferred embodimentthereof, it is evident that many alternatives, modifications andvariations will be apparent to those skilled in the art. Accordingly, itis intended to embrace all such alternatives, modifications andvariations as fall within the spirit and broad scope of the appendedclaims.

What is claimed is:
 1. An electrophotographic printing machine forforming an edited copy of an original document, including:aphotoconductive member; means for charging at least a portion of saidphotoconductive member; means for sensing an optical image andgenerating an electrical video image in response thereto; means forforming a light image of the original document, said forming meansprojecting the light image of the original document onto said sensingmeans to produce an electrical video image thereof, and said formingmeans projecting the light image of the original document onto thecharged portion of said photoconductive member to record anelectrostatic latent image of the original document thereon; means forediting the electrostatic latent image by adding or deleting informationfrom the electrostatic latent image so that the copy differs from theoriginal document; and means, operatively associated with said sensingmeans, for displaying the electrical video image of the edited originaldocument to provide a preview of the edited copy.
 2. A printing machineaccording to claim 1, further including means for depositing markingparticles on the electrostatic latent image to form a powder image onsaid photoconductive member.
 3. An electrophotographic printing machinefor forming an edited copy of an original document, including:aphotoconductive member; means for charging at least a portion of saidphotoconductive member; means for sensing an optical image andgenerating an electrical video image in response thereto; means forforming a light image of the original document, said forming meansprojecting the light image of the original document onto said sensingmeans to produce an electrical video image thereof, and said formingmeans projecting the light image of the original document onto thecharged portion of said photoconductive member to record anelectrostatic latent image of the original document thereon; means,operatively associated with said sensing means, for displaying theelectrical video image; means for editing the electrostatic latent imageso that the copy differs from the original document; means fordepositing marking particles on the electrostatic latent image to form apowder image on said photoconductive member; and means, operativelyassociated with said sensing means, for controlling said depositingmeans to regulate the contrast of the copy formed in the printingmachine.
 4. A printing machine according to claim 3, further includingmeans for dispensing marking particles into said depositing means.
 5. Aprinting machine according to claim 4, further including means,operatively associated with said sensing means, for regulating saiddispensing means to regulate the discharge of marking particles intosaid depositing means.
 6. An electrophotographic printing machine forforming an edited copy of an original document including:aphotoconductive member; means for charging at least a portion of saidphotoconductive member; means for sensing an optical image andgenerating an electrical video image in response thereto; means forforming a light image of the original document, said forming meansprojecting the light image of the original document onto said sensingmeans to produce an electrical video image thereof, and said formingmeans projecting the light image of the original document onto thecharged portion of said photoconductive member to record anelectrostatic latent image of the original document thereon; means,operatively associated with said sensing means, for displaying theelectrical video image; means for editing the electrostatic latent imageso that the copy differs from the original document; and means,operatively associated with said editing means, for controlling saidcharging means to regulate the voltage level on said photoconductivemember, thereby adjusting the contrast of the copy formed by theprinting machine.
 7. An electrophotographic printing machine for formingan edited copy of an original document, including:a photoconductivemember; means for charging at least a portion of said photoconductivemember; means for sensing an optical image and generating an electricalvideo image in response thereto; means for forming a light image of theoriginal document, said forming means projecting the light image of theoriginal document onto said sensing means to produce an electrical videoimage thereof, and said forming means projecting the light image of theoriginal document onto the charged portion of said photoconductivemember to record an electrostatic latent image of the original documentthereon; means, operatively associated with said sensing means, fordisplaying the electrical video image; means for editing theelectrostatic latent image so that the copy differs from the originaldocument; and means, operatively associated with said editing means, forcontrolling said forming means to regulate the intensity of the lightimage projected onto the charged portion of said photoconductive member,thereby adjusting the contrast of the copy formed in the printingmachine.
 8. A printing machine according to claim 7, further includingmeans, operatively associated with said editing means, for controllingsaid forming means to regulate the size of the light image projectedonto the charged portion of said photoconductive member, therebyadjusting the magnification of the copy formed in the printing machine.9. An electrophotographic printing machine for forming an edited copy ofan original document including:a photoconductive member; means forcharging at least a portion of said photoconductive member; means forsensing an optical image and generating an electrical video image inresponse thereto; means for forming a light image of the originaldocument, said forming means projecting the light image of the originaldocument onto said sensing means to produce an electrical video imagethereof, and said forming means projecting the light image of theoriginal document onto the charged portion of said photoconductivemember to record an electrostatic latent image of the original documentthereon; means, operatively associated with said sensing means, fordisplaying the electrical video image; means for editing theelectrostatic latent image so that the copy differs from the originaldocument; and means, operatively associated with said editing means, forcontrolling said forming means to regulate the position of the lightimage projected onto the charged portion of said photoconductive member,thereby adjusting the shift of the image reproduced on the copy by theprinting machine.
 10. An electrophotographic printing machine forforming an edited copy of an original document, including:aphotoconductive member; means for charging at least a portion of saidphotoconductive member; means for sensing an optical image andgenerating an electrical video image in response thereto; means forforming a light image of the original document, said forming meansprojecting the light image of the original document onto said sensingmeans to produce an electrical video image thereof, and said formingmeans projecting the light image of the original document onto thecharged portion of said photoconductive member to record anelectrostatic latent image of the original document thereon; means,operatively associated with said sensing means, for displaying theelectrical video image; means for editing the electrostatic latent imageso that the copy differs from the original document; means fordepositing marking particles on the electrostatic latent image to form apowder image on said photoconductive member; and means, operativelyassociated with said editing means, for deleting selected areas of theelectrostatic latent image recorded on said photoconductive member. 11.A printing machine according to claim 10, wherein forming means projectsat least two light images of the original document onto the chargedportion of said photoconductive member to record a first electrostaticlatent image and a second electrostatic latent image on saidphotoconductive member.
 12. A printing machine according to claim 11,wherein said deleting means deletes one region from the firstelectrostatic latent image recorded on said photoconductive member toform a first edited electrostatic latent image and the other region fromthe second electrostatic latent image recorded on said photoconductivemember to form a second edited electrostatic latent image.
 13. Aprinting machine according to claim 12, wherein said depositing meansdevelops the first edited electrostatic latent image with markingparticles of a first color and said depositing means develops the secondedited electrostatic latent image with marking particles of a secondcolor different from the first color.
 14. A printing machine accordingto claim 10, wherein said sensing means includes at least a chargecoupled device.
 15. A printing machine according to claim 14, whereinsaid displaying means includes at least a cathode ray tube.
 16. Aprinting machine according to claim 14, wherein said displaying meansincludes at least a liquid crystal display.
 17. A printing machineaccording to claim 10, further including a plurality of processingstations for assisting in producing the copy of the original documentfrom the electrostatic latent image recorded on said photoconductivemember.
 18. A printing machine according to claim 17, further including,means for controlling at least one of said plurality of processingstations to produce an adjusted copy of the original document.